The animal resource facility in Thimann Laboratories, University of California, Santa Cruz, California, provides an essential support facility for a number of active biomedical research programs on this campus. Constructed in 1966, and expanded in 1968 and 1969, the building cannot at present conform with the Animal Welfare Act of 1970. In order to continue current health-related research, and to come in compliance with current federal regulations, a number of modifications are required. The purpose of the present application is to obtain funds for the purposes of structural renovations and equipment purchases, which will enable the UCSC facility to operate within the NIH guidelines and to provide efficient and economical animal care for ongoing and immediately anticipated research programs.